my kia sephia 1995 RPM fluctuate when I put any electrical load on iT on 1995 Kia Sephia

THE RPM GOES DOWN QUICKLY AND THEN THE CAR ENGINE TRIES TO RECOVER IT, BUT IT STARTS SHACKING AFTER, MY BATTERY IS ACCEPTABLE AND THE ALTERNATOR IS GOOD, I CANGED THE SENSORS.. SOME TIMES IT DOES NOT START AT ALL, I REMOVE THE FUSE RESPONSIBLE FOR BENZEN PUMP AND PUT IT BACK THEN IT STARTS